In fact, the thing I'd suggest you getting would be a 30 gallon tank (or preferably bigger) for them babies of yours (: In a good "package" you could get the gravel, lamp and filter as a part of the bargain
You have two common goldfish, and these two would grow to about a foot in length if cared for well, and they could live for up to 30 years! Therefore, these guys need a big, well filtered tank for them to move about! A 30 gallon is absolute minimum!
Goldfish are extremely dirty, and they need lots of oxygen to stay healthy. So if you really care for these fish of yours, you'll buy them a proper tank! (: